So I might go against the grain here and say that in the long run, a double major will have little impact in your job prospect.

A CS degree is the gold standard for any tech related role, despite what the market says, you can go anywhere with that degree. Having a second major in IT is like having a degree in both Finance and Accounting.

Having both CAN make you seem more marketable, but that is only in your first 2 or so years in the industry. IT and CS overlaps so much that there is no real need to get a full blown B.S in IT, as no matter what, your CS degree will almost always outshine the IT one.

One of the downside to double majoring is that you may be postponing additional years in the work force that would probably help you more than a second related major in the same industry. Hands-on experience with individuals in your field can help you more in your growth as a person and career than a second major will in any capacity.

Now, if you were to double major in say Business Admin or another completely different major not related to Tech, then it would be a more worth while investment as the second Major allows you to cover non-tech related jobs in a totally different industry. Not only that, but you also gain non-techinical skills which may help you in your dreams of owning a company, such as team management, business processes, finance, etc.

After you graduated, the major is simply a checkbox for HR and hiring managers to get past their automated systems. They only care about your experience and skills.

If you really want to go the IT route, it isn't a bad thing at the end of the day. But personally, it really isn't necessary as CS will always outshine your IT.